Solved! Go to Solution.
Take a look at this thread and see if it helps to explain as it helped me ...
http://forums.arcgis.com/threads/57375-Why-would-I-install-ArcSDE-with-10.1
and this...
http://blogs.esri.com/esri/supportcenter/2012/03/27/where-did-the-arcsde-post-installation-wizard-go...
Carmen